go module 实践

• Go Modules Reference - The Go Programming Language
• 跳出 Go module 的泥潭 | 鸟窝

什么是 go module

• go module

  • go 的新依赖管理系统

  • Go 1.11 和 1.12 初步支持

    • 在

      $GOPATH

      外部

      • 前两者通过检测当前文件夹和父文件夹里的 go.mod

    • 在

      $GOPATH

      内部

      • 使用 GOPATH 模式，即使存在 go.mod 情况下

  • 1.13 默认使用

  • A collection of Go packages sotred in a file tree with a

    go.mod

    file at its root

    • Go 程序通过连接多个packages构成
    • package 由多个源代码文件构成，它们一起声明了常量、类型、变量、函数和它的外部可访问性

  • 只出现在 module 的根文件夹

    • 子文件夹下的 package = <modulel path> + <the subdirectory>
    • 子文件夹出现 go.mod 将视为独立的 module

  • 执行步骤

    • 解析版本

      @<version>

      • @latest

      • @none

      • @upgrade = -u

      • @patch = -u=patch

      • @v1

      • @v2

      • @<branch>

      • @<commit hash>

      • 冲突解决

        If thereare competing requirements for a particular module, then ‘go get’ resolvesthose requirements by taking the maximum requested version.

      • go list -m -versions 192.168.1.254/xx/xxx

      • go list -m -versions all

    • download if needed

    • build

    • install

  • go 命令会自动补全 go.mod 里缺失的 modules，默认使用 @latest 版本

  • go 命令同时维护着包含特殊 module 版本的密码学哈希的文件 go.sum

  • go.mod 和 go.sum 应该被放到版本管理里

  • A semantic version has three parts: major, minor, and patch.

  • Each different major version (

    v1

    ,

    v2

    , and so on) of a Go module uses a different module path: starting at

    v2

    , the path must end in the major version.

    • If an old package and a new package have the same import path, the new package must be backwards compatible with the old package.
    • By definition, a new major version of a package is not backwards compatible with the previous version. This means a new major version of a module must have a different module path than the previous version.

go mod init example.com/hello # create a new module, initializing the go.mod file
go list -m all # 列出所有的 packages 和它们的子依赖

go list -m -versions rsc.io/sampler
rsc.io/sampler v1.0.0 v1.2.0 v1.2.1 v1.3.0 v1.3.1 v1.99.99

go get rsc.io/sampler@v1.3.1 # changes the required version of a dependency (or adds a new dependency)

go list -m -versions rsc.io/quote/v3
rsc.io/quote/v3 v3.0.0 v3.1.0

go mod tidy # remove unused dependencies

go package 相关问题

• 相对导入

  go - relative import paths

  • An import path beginning with ./ or ../ is called a relative path.
  • First, a relative path can be used as a shorthand on the command line.
  • Second, if you are compiling a Go program not in a work space, you can use a relative path in an import statement in that program to refer to nearby code also not in a work space.
  • To avoid ambiguity, Go programs cannot use relative import paths within a work space.

• Code in or below a directory named “internal“ is importable only by code in the directory tree rooted at the parent of “internal”.

• vendor directories

  • Code in or below a directory named “internal“ is importable only by code in the directory tree rooted at the parent of “internal”.

• Module proxy protocol

git仓库相关问题

• git 支持哪些协议

  • local protocol
  • HTTP protocols
    • smart HTTP
    • dumb HTTP
  • SSH protocol
  • Git protocol
    • TCP port 9418
    • no authentication
    • latest version is v2

• 如何使用 go get 下载 gitlab 私有项目

  • 内网Gitlab如何鉴权

    FAQ - Why does “go get” use HTTPS when cloning a repository - golang.org

    • 使用 SSH 私钥
      • git config --global --add url."git@192.168.1.254:".insteadOf "<http://192.168.1.254/>"
      • ~/.gitconfig
    • 使用密码或 token (Github, Gitlab)
      • ~/.netrc

  • 如何访问 HTTP 而不是 HTTPS

    • go get -insecure 192.168.1.254/xxx/xxxx
    • go env -w 'GOINSECURE=*.example.com,*.example2.com'

GOPROXY

• GOPROXY.IO - 一个全球代理 为 Go 模块而生
  • GO111MODULE
  • GOPROXY
  • GOPRIVATE: a default value for GONOPROXY and GONOSUMDB.

GOSUMDB

• GOSUMDB 环境变量

常见 Go 代码托管仓库

• github.com
• gitlab.org
• bitbucket.org
• golang.org
• go.uber.org
• gopkg.in
• k8s.io
• go.mongodb.org

使用问题

go get -insecure xxx@master: xxx@master: invalid version: unknown revision master

• Go version: go1.15.2
• 可能原因
  • Go: go mod获取第三方依赖包 unknown revision xxx 错误解决
    • 通过 Install latest Git 解决：失败
  • Go 如何解析版本
    • go/git.go at 3840aced142aeeca6ddf54cb90c07b54e4cf814b · golang/go
    • loadRefs go/git.go at 3840aced142aeeca6ddf54cb90c07b54e4cf814b · golang/go L174
  • 通过在 ~/.netrc 配置内网 gitlab 访问 token 可解决

meta data 不匹配

> go get -v git.xxx.com/xx/go-lib-websocket@gomod
go get git.xxx.com/xx/go-lib-websocket@gomod: unrecognized import path "git.xxx.com/xx/go-lib-websocket": parse <http://git.xxx.com/xx/go-lib-websocket?go-get=1:> no go-import meta tags (meta tag 192.168.1.254/xx/go-lib-websocket did not match import path git.xxx.com/xx/go-lib-websocket)

迁移到 git module

• 历史版本管理工具
  • dep
  • glide
• 如何从历史版本管理工具迁移
  • go mod init creates a new go.mod file and automatically imports dependencies from Godeps.json, Gopkg.lock, or a number of other supported formats.
• 如何从内网git仓库迁移到类似github的标准仓库
  • 必须加域名，否则代码里充斥了很多 IP
  • 加了域名，相当于包名都改了
  • 所有引用它的包都要改引用方式，改动量非常大
  • 临时方案
    • 在本地用 replace 方式引用
    • 改动本地的库的名字，以及库里代码的引用名字
• remote import paths 如何工作
  • go - Remote import paths
    • When using GOPATH, downloaded packages are written to the first directory listed in the GOPATH environment variable. (See ‘go help gopath-get’ and ‘go help gopath’.)
    • When using modules, downloaded packages are stored in the module cache. (See ‘go help module-get’ and ‘go help goproxy’.)
• 最终方案：

go mod 小范围迁移方案